1. Field of the Invention
The present invention relates to catheters. More particularly, the present invention relates to a cardioplegia catheter having an echogenicity enhancement to aid in detecting the position of the catheter within a body.
2. Description of the Related Art
Catheters have a wide variety of applications during surgical procedures. For example, in cardiac surgery, venous and arterial catheters are used to conduct blood between the body and bypass equipment. Catheters are used to conduct cardioplegic solutions for both antegrade and retrograde solution administration. Cardioplegic solutions, typically containing potassium, magnesium, procaine or a hypocalcemic solution, stop the heart by interfering with the heart's capacity to conduct the natural electric signals which cause beating of the heart. In normal antegrade cardioplegia, a single needle is inserted into the aorta, and cardioplegic solution is administered therethrough. The cardioplegic solution flows through the coronary arteries in the normal direction of blood flow. In retrograde cardioplegia, a balloon catheter is inserted into the coronary sinus. The balloon is then inflated, and the cardioplegic solution is perfused through the coronary veins in the opposite direction of blood flow.
Traditional cardiac surgery involves creating a large incision in the chest cavity to expose the heart. Under these surgical conditions proper placement of a catheter may be determined by either direct visual or sensory cues. However, a recent trend in surgical procedures is to minimize the size of access apertures formed in the chest cavity, thereby making it more difficult to confirm whether a catheter is properly positioned within the body and specifically within the aorta or coronary sinus. In these procedures, generally referred to as "Minimally Invasive Cardiac Surgery," the size of the aperture in the chest wall is reduced to a size slightly larger than that of the catheter to be inserted therein. As a result, other methods are needed to determine the location of the catheter within the body.
One way of confirming the location of a catheter within a body is with an ultrasonic pulse-echo imaging system. The term "echogenicity" refers to the relative extent that a surface reflects incident ultrasound wave energy directly back to a sensor, which is proximate the source or emitter of the ultrasonic wave energy. The low practical echogenicity of the prior art smooth catheters hampers accurate imaging of the catheter within the body. Typically, a needle or stylet of the catheter, or at least its point or tip, is echogenically enhanced to improve its ultrasound image, in order to more accurately pinpoint its placement during real-time ultrasonic guidance. Once the catheter is in place, the stylet is removed from the catheter. One disadvantage to this arrangement is that a needle or stylet is required in order to accurately determine the position of the catheter within the body. At times it may be desirable to use a catheter without a needle or stylet inserted therein.
There is a need, therefore, for an improved catheter having an echogenicity enhancement provided on the catheter itself. In addition, there is a need for an echogenically enhanced catheter that has smooth exterior and interior surfaces, so as not to interfere with insertion of the catheter into the body or with the transport of liquids therethrough.